1. Field of the Invention
This invention relates to a navigation device that can display simulated navigation data. The device find particular application as an in-car navigation system.
2. Description of the Prior Art
GPS based devices are well known and are widely employed as in-car navigation systems. Reference may be made to the Navigator series software from the present assignee, TomTom B. V. This is software that, when running on a PDA (such as a Compaq iPaq) connected to an external GPS receiver, enables a user to input to the PDA a start and destination address. The software then calculates the best route between the two end-points and displays instructions on how to navigate that route. By using the positional information derived from the GPS receiver, the software can determine at regular intervals the position of the PDA (typically mounted on the dashboard of a vehicle) and can display the current position of the vehicle on a map and display (and speak) appropriate navigation instructions (e.g. ‘turn left in 100 m’). Graphics depicting the actions to be accomplished (e.g. a left arrow indicating a left turn ahead) can be displayed in a status bar and also be superimposed over the applicable junctions/turnings etc in the roads shown in the map itself. Reference may also be made to devices that integrate a GPS receiver into a computing device programmed with a map database and that can generate navigation instructions on a display. The term ‘navigation device’ refers to a device that enables a user to navigate to a pre-defined destination. The device may have an internal system for receiving location data, such as a GPS receiver, or may merely be connectable to a receiver that can receive location data.
Route preview functions are known for GPS vehicle navigation systems. For example, in U.S. Pat. No. 5,544,060 (Zexel USA Corporation), a route is calculated to a destination and the directions for this route, as represented by simple arrows indicating the direction of travel and the current street name, can be sequentially displayed before the time of travel to allow the driver to familiarise himself with the route to be followed. In U.S. Pat. No. 6,249,742 Navigation Technologies Corp.), a preview comprising the names of roads on a calculated route (but not detailed manoeuvring instructions or an animated map) can be generated and displayed. In U.S. Pat. No. 5,832,406 (Alpine electronics, Inc.), the route preview function shows a sequence of images of all the major turnings etc., but no actual animated map In U.S. Pat. No. 5,612,881 (Aisin AW Co., Ltd.), an animated map is shown during the preview, but the information displayed is quite limited and no road names are displayed. The present invention aims to improve over this art.